Turbulators or baffles are frequently used in heat exchanger tubes to increase the efficiency of the heat transfer. The turbulator acts to create turbulence and mixing within the heat exchanger tube, thereby increasing the rate of heat transfer. In a combustion system, efficient heat transfer results in condensation of water vapor. As condensation is a heat generating process, the heat produced through condensation can be utilized to further increase the efficiency of the heat transfer operation.
In the past, various forms of turbulators or baffles have been utilized in heat exchanger tubes. The turbulators should not only increase turbulence, but they should not produce undesirable back pressure and may be required to withstand severe environmental conditions. During service, the turbulators may be exposed to extreme elevated temperatures, as well as to acidic condensate.
In a conventional gas-fired water heater, the gas burner is located beneath the lower head of the tank and waste gases of combustion from the burner pass upwardly through one or more flues that extend through the tank. With this construction, heat is transferred from the burner through the lower head to the water in the tank, as well as from the waste gases passing through the flue to the water.
To increase the rate of heat transfer from the gases of combustion to the water, a baffle or turbulator is normally mounted within the flue. Various contours and configurations of turbulators have been employed with a water heater and a common turbulator is fabricated from a sheet of metal, which is twisted into the form of a helix.